Method for Using a Disposable Bioreactor

ABSTRACT

In one embodiment, a disposable bioreactor including a headplate and a stirrer. The headplate has at least one inlet port aperture and one outlet port aperture formed therein and is adapted to couple sealingly with a bag capable of receiving a culture medium. The stirrer is coupled to and extends from the headplate and is adapted to stir the culture medium when the headplate is coupled to the bag. The bioreactor is adapted to fit within the upper opening of the stand of an existing conventional glass bioreactor, so that the bag is suspended within the vessel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 15/038,194,filed on May 20, 2016 as attorney docket no 1020.019, which claims thebenefit of the filing date of PCT patent application no. PCT/US14/66977,filed on Nov. 21, 2014 as attorney docket no. 1020.019PCT, which claimsthe benefit of the filing date of U.S. provisional application No.61/907,146, filed on Nov. 21, 2013 as attorney docket no. 1020.019PROV,the teachings of all of which are incorporated herein by reference intheir entirety.

FIELD OF THE INVENTION

The present invention relates generally to the growth of biologicalcultures and, in particular, to bioreactors for biologically-activesubstances.

BACKGROUND OF THE INVENTION

A bioreactor is a vessel or container used for the growth of biologicalcultures, such as cells, bacteria, yeasts, or fungi. These cultures areused to produce a variety of biologically-active substances, includingpharmaceuticals, fragrances, fuel, and the like.

A conventional bioreactor vessel has a cylindrical shape and includes amixing apparatus, means for introducing a gas supply, and a temperaturecontrol system. Most bioreactor applications require a sterilizationprocess to ensure that the process run does not yield the growth of, orcontamination from, undesirable biological organisms. Traditionalmethods of sterilizing bioreactors include the use of an autoclave (forsmaller vessels) or a steam sterilization-in-place process (for largervessels). In recent years, there has been an introduction of single-usebioreactors. A conventional single-use bioreactor is typically deliveredto the end user in the form of a pre-sterilized container and is usedfor only a single process run, after which the user disposes of thesingle-use bioreactor.

Typical materials of construction for small autoclavable bioreactorvessels may include, e.g., a glass vessel with a stainless steel cover,tube, and sensor adapters, mixing apparatus, and baffles. These vesselsare filled with culture media and are then carried to an autoclave,where they are sterilized for several hours. The vessel is then takenback to the laboratory, where it is allowed to cool down. The vessel isthen connected to a control system, which is used to controltemperature, agitation, aeration and pH. The vessel is subsequentlyinoculated with the desired organism, at which time the process runproceeds.

While this has been the method of choice for process development for thelast half century, the problem with this method is that the process isvery time- and labor-consuming. Each process run typically lasts 1 to 10days. Between each run, the vessel must be manually cleaned andsterilized in the autoclave. This can result in a turnaround time of 1to 3 days between runs. As a result, the single-use bioreactor wasdeveloped to allow the end user to eliminate the sterilization andcleaning portion of the process. At the end of each run, the vessel isdiscarded, and a new pre-sterilized vessel is removed from the packagingand is set up to start the next run.

A typical single-use bioreactor employs a medical-type bag that rests ontop of a platform, where an orbital or rocking motion is induced to mixand aerate the organism. However, a problem with this type of system isthat the mixing action and oxygen transfer are limited, resulting in alow organism growth density relative to the design of a traditionalagitator and sparger (a device that bubbles gas through the bioreactor)in a “stirred tank” bioreactor. In addition, the different mixing motionand bag geometry in the medical-type bag bioreactor does not lend itselfto be scaled up to larger production processes. Further, in order for ascientist to use one of the medical-type bag single-use rocking systems,the scientist is required to invest substantial capital and laboratoryspace in an additional piece of specialized equipment.

These limitations of the initial single-use bioreactor designs have ledto the development of “stirred-tank” single-use bioreactor products.

One type of stirred-tank single-use bioreactor product employs abag-type vessel containing a mixer, sparger, sensors, and tubing. Thebag is placed into a structure of some type (typically a stainlesscylinder) and conforms to its shape. The intent is for the bag to mimica traditional stainless-steel or glass stirred-tank bioreactor. However,the design does not lend itself to small vessel sizes (e.g., less than50L), because the size of the fittings in the bag and the number offittings for a standard bioreactor exceed the allowable accessiblesurface area on the bag.

Another type of stirred-tank single-use bioreactor product employs arigid plastic vessel that is self-supporting and has a self-containedmixing apparatus, aeration system, and sensors. This type of unit mimicsthe look and feel of a traditional stainless-steel or glass-typebioreactor vessel. However, unlike a single-use bag system, the rigidplastic used in this design cannot be folded or reduced in size forstorage or disposal. This burdens the end user with a requirement for alarge environmentally-controlled area within the user's facility forstorage of future vessels, as well as increased disposal costsassociated with such larger, non-compressible vessels.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a top-side perspective view of a disposable bioreactorconsistent with one embodiment of the invention;

FIG. 2 shows a top perspective view of the disposable bioreactor of FIG.1;

FIG. 3 shows a side perspective view of the disposable bioreactor ofFIG. 1;

FIG. 4 shows a bottom perspective view of the disposable bioreactor ofFIG. 1;

FIG. 5 shows a partial cross-sectional view of a portion of thedisposable bioreactor of FIG. 1; and

FIG. 6 shows a side perspective view of a conventional glass bioreactor;

FIG. 7 shows side perspective view of the headplate and internalcomponents of the conventional glass bioreactor being removed from theglass vessel; and

FIG. 8 shows a side perspective view of the disposable bioreactor ofFIG. 1 being installed into the glass vessel of the conventional glassbioreactor.

DETAILED DESCRIPTION

With reference to FIGS. 1-6, a disposable bioreactor 100 consistent withone embodiment of the invention is illustrated. The features describedbelow are generally visible in FIG. 1, unless otherwise indicated.

Bioreactor 100 includes a circular headplate 101 that serves as asupport for a vessel liner 102 (shown in broken lines). Vessel liner 102is a flexible bag in which a culture medium is disposed, and in whichorganisms are grown in the culture medium. These organisms may besubmerged (e.g., suspended or immobilized) in a liquid medium disposedwithin vessel liner 102, or attached to the surface of a solid mediumdisposed within vessel liner 102.

Headplate 101 also serves as a support for various additional componentsmounted on and through headplate 101. These additional components mayvary in different embodiments of the invention. In this embodiment, theadditional components include the following:

A dissolved oxygen (DO) sensor (not shown) is housed within DO tubing103, which is a length of platinum-cured silicon tubing that passesthrough headplate 101 and has a probe cover 104 at its bottom end. DOprobe (not shown) may be, e.g., a galvanic (electrochemical) dissolvedoxygen sensor, an optical sensor, or another type of sensor that detectsdissolved oxygen in the culture medium disposed within vessel liner 102.DO tubing 103 houses wiring (not shown) that couples DO probe (notshown) to a manual or automatic monitoring mechanism, transmitter,processor, or the like, via an interface (not visible in the figures)disposed on the upper surface of headplate 101.

A cell harvest tube 105 is formed from a length of platinum-curedsilicon or weldable TPE tubing that passes through headplate 101. Cellharvest tube 105 has, at its bottom end, an open tip that may be taperedand is desirably disposed as close to the bottom of vessel liner 102 aspossible, to maximize harvesting of cells. The other end of cell harvesttube 105 is coupled to a manual or automatic pump or pipettingmechanism, or the like, via a coiled portion 127 that permits extensionof cell harvest tube 105 to a length of approximately 76 cm. andincludes a tubing clamp 130 near its free end. To enable such couplingof cell harvest tube 105, the free end of coiled portion 127 leads to amale MPC-type sealing plug 128 mounted to coiled portion 127 via anMPC-type hose barb non-valved in-line coupling body 129. Coupling body129 is secured to the free end of coiled portion 127 using a standardwire tie 140, which is also the case with most other tubing connectionsof bioreactor 101, as seen throughout FIGS. 1-4.

A sparger tube 106 is formed from a length of platinum-cured silicontubing that passes through headplate 101. At its upper end, sparger tube106 is coupled to a gas supply via a validatable inlet filter 131disposed inline at the upper end of sparger tube 106. The other (i.e.,bottom) end of sparger tube 106 is securely coupled to a polyethylenemicro-sparger 107, which is disposed near the bottom of vessel liner 102and bubbles a chemically-inert gas through the culture medium disposedwithin vessel liner 102. Standard wire ties 140 are used to secure inletfilter 131 to the free end of sparger tube 106, and also to secure inletfilter 131 to headplate 101.

A sampling tube 121 is formed from a length of platinum-cured silicon orweldable TPE tubing that passes through headplate 101. Sampling tube 121permits samples of the culture medium to be removed for analysis andhas, at its bottom end, an open tip that may be tapered. The other endof sampling tube 121 is coupled to a manual or automatic pump or syringemechanism, or the like, via a coiled portion 132 that permits extensionof sampling tube 121 to a length of approximately 51 cm. and includes atubing clamp 130 near its free end. To enable such coupling of samplingtube 121, the free end of coiled portion 132 leads to a needleless maleluer-type connector 133 mounted to coiled portion 132. Standard wireties 140 are used to secure male luer-type connector 133 to the free endof sampling tube 121, and also to secure sampling tube 121 to headplate101.

A sensor tube 122 is formed from a length of platinum-cured silicontubing that passes through headplate 101. Sensor tube 122 has anon-invasive pH or DO sensor 123 mounted at its bottom end by means of aplug insert 126, secured using a standard wire tie 140. Sensor tube 122houses wiring (not shown) that couples the pH or DO sensor 123 to amanual or automatic monitoring mechanism, transmitter, processor, or thelike, via a pH or DO interface 134 disposed on the upper surface ofheadplate 101.

A temperature sensor tube 124 is formed from a length of platinum-curedsilicon tubing that passes through headplate 101. Temperature sensortube 124 has a temperature sensor 125 seated at its bottom end by meansof a plug insert 126. Temperature sensor tube 124 houses wiring (notshown) that couples temperature sensor (not shown) to a manual orautomatic monitoring mechanism, transmitter, processor, or the like, viaa temperature interface 135 disposed on the upper surface of headplate101.

Three smaller addition tubes 136 and two larger addition tubes 137(e.g., for introducing liquids into the culture medium) are formed fromlengths of platinum-cured silicon or weldable TPE tubing that passesthrough headplate 101. At their bottom ends, each of addition tubes 136,137 leads to a respective aperture (or short length of tubing) on theunderside of headplate 101. The top ends of each addition tube 136 canbe coupled to a manual or automatic pump or pipetting mechanism, or thelike, via respective coiled portions 138, 139 that permit extension ofaddition tubes 136, 137 to lengths of approximately 51 cm. andapproximately 76 cm., respectively. Each coiled portion 138, 139includes a tubing clamp 130 near its free end. The free end of eachcoiled portion 138 of smaller addition tubes 136 leads to a respectiveneedleless male luer-type connector 141 mounted to coiled portion 138.Standard wire ties 140 are used to secure male luer-type connector 141to the free end of smaller addition tubes 136, and also to securesmaller addition tubes 136 to headplate 101. The free end of each coiledportion 139 of larger addition tubes 137 leads to a respective maleMPC-type sealing plug 142 mounted to coiled portion 139 via an MPC-typehose barb non-valved in-line coupling body 143. Standard wire ties 140are used to secure coupling body 143 to the free end of larger additiontubes 137, and also to secure larger addition tubes 137 to headplate101.

A gas addition port (not visible in the figures) consisting of anaperture (or short length of tubing) on the underside of headplate 101leads to a short length of platinum-cured silicon gas-addition tubing(not visible in the figures) that passes through headplate 101. Avalidatable inlet filter 146 (shown in FIG. 2) is disposed inline at theupper end of gas-addition tubing 144. A standard wire tie (not visiblein the figures) is used to secure inlet filter 146 to the free end ofthe gas-addition tubing, and also to secure the gas-addition tubing toheadplate 101.

An exhaust port (not visible in the figures) consisting of an apertureon the underside of headplate 101 leads to a short length ofplatinum-cured silicon exhaust tubing 144 that passes through headplate101. A validatable inlet filter 145 is disposed inline at the upper endof exhaust tubing 144. A standard wire tie 140 is used to secure inletfilter 145 to the free end of exhaust tubing 144, and also to secureexhaust tubing 144 to headplate 101.

A stirring mechanism is formed from a shaft 108 rotatably mounted toheadplate 101, with an impeller 109 mounted at the bottom end of shaft108. Impeller 109, which has three generally semi-circular pitchedblades, is secured to the end of shaft 108 via an o-ring 110 (shown inFIGS. 3 and 4). In alternative embodiments, shaft 108 may be foldable,telescoping, or in multiple hinged or otherwise joinable portions, topermit compact storage and transport.

FIG. 5 is a partial cross-sectional view showing details of theinterface between shaft 108 and headplate 101, which includes a magneticdrive assembly for impeller 109 to stir the culture medium. In FIG. 5,broken line 118 represents, generally, the plane of the culturemedium-facing side (i.e., underside) of headplate 101. As shown, apermanent magnet 115 is coupled to shaft 108, and both shaft 108 andmagnet 115 are disposed to freely rotate in tandem within the structureof an upper bearing 113 and a lower bearing 114 that capture shaft 108.A generally-cylindrical extended portion 117 is formed in headplate 101to provide clearance for the magnetic drive assembly, while desirablymaintaining magnet 115 above headplate 101.

Shaft 108 is rotatably disposed within bearings 113, 114, with magnet115 disposed between upper bearing 113 and lower bearing 114 androtating within but not contacting the interior surface 120 ofgenerally-cylindrical extended portion 117.

Bearings 113 and 114 are desirably polymer bearings that areself-lubricating. During the molding step of the fabrication of bearings113, 114, solid lubricants are embedded within reinforcing fibers of thebearings. These solid lubricants reduce friction and enhance wearresistance of bearings 113, 114, which form a dry-running surface forshaft 108 to rotate in the magnetic field of magnet 115 while supportedby bearings 113, 114. A retaining ring 111 is disposed on shaft 108above magnet 115 to position shaft 108 within extended portion 117.Lower bearing 114 is supported by a drive retention bracket 112, whichis coupled to headplate 101 via three screws 165 (shown in FIG. 4). Eachscrew 165 (or bolt, or other fastener) is driven through drive retentionbracket 112, a respective press-fit expansion insert 116 (only one ofwhich is shown in FIGS. 4 and 5), and headplate 101.

The exterior surface 119 of extended portion 117 is adapted to receive adriving assembly (not shown) having a recessed portion that matches thecontours of exterior surface 119 of extended portion 117. The drivingassembly employs a motor-driven drive magnet that rotates around portion117 to cause magnet 115 to spin in synchronization. The attraction ofthe motor-driven drive magnet and magnet 115 passes substantially all ornearly all of the torque of the motor onto shaft 108. Accordingly, thedriving assembly remains isolated from the culture medium inside vesselliner 102 and from the magnetic drive assembly of bioreactor 100,thereby eliminating potential hazards from leakage associated with shaftseals.

As best seen in FIGS. 3, 4, and 6-8, headplate 101 has a cylindricalcollar 151 formed on its underside and adapted to retain vessel liner102. As shown in FIGS. 6-8, collar 151 is also adapted to fit within theupper opening of the glass vessel 161 of an existing conventional glassbioreactor, after the headplate 168 and internal components have beenremoved, thereby permitting disposable bioreactor 100 to replace thesecomponents and use the same glass vessel and stand 169. One or moreapertures 152 of headplate 101 may be used to secure bioreactor 100 tostand 169, e.g., using screws or bolts 170. Bioreactor 100 can be placedin other types of rigid structures as well.

In one exemplary method for operating bioreactor 100, a culture mediumis first loaded via one or more of addition tubes 136, 137 and the gasaddition port. The impeller 109 is then activated by the external driveassembly, as described above, to begin stirring. Gas flow throughsparger tube 106 is then initiated. Temperature within the bioreactor iscontrolled to a set point based on the reading of the temperature sensor(not shown) and with energy supplied by a device such as a externalheater blanket (not shown). Dissolved oxygen is measured via DO probe(not shown), and pH is measured via pH sensor 123. The culture medium isseeded with cells, which are loaded, e.g., via one or more of additiontubes 136, 137. The culture medium is sampled via sampling tube 121.Once cell growth is complete, the cells are harvested via cell harvesttube 105. Other operations may take place in alternative embodiments andin connection with alternative applications for the use of bioreactor100.

Thus, a bioreactor consistent with embodiments of the invention employsa hybrid design that includes features of both a bag-style design and arigid plastic stirred-tank design. Headplate 101 may be rigid orelastomeric and is desirably joined to flexible vessel liner 102, e.g.,by means of welding, mechanically fastening, elastomeric sealing, heatsealing, or the like. Vessel liner 102 is desirably sealed to headplate101 so that the inside of vessel liner 102 remains sterile. Headplate101 may also have shapes other than those illustrated or describedherein.

Impeller 109 may, in alternative embodiments, include other types andconfigurations of stirring apparatus, including, e.g., a propeller-typeimpeller, a straight-blade impeller, and so forth. Accordingly, the term“stirrer” should be understood to include a motor-driven impeller asdescribed herein, as well as other apparatus capable of stirring theculture medium inside the vessel liner.

Although not shown in the figures, other inlets, outlets, and ports maybe employed in other embodiments. For example, a carbon dioxide sensorand/or a pressure sensor may be included.

Since a bioreactor consistent with embodiments of the inventiongenerally employs the same types of connectors as conventionalbioreactors and provides generally the same functionality, a scientistcan utilize existing glass bioreactors and control systems that thescientist has already been using in an autoclave and convert those glassbioreactors and control systems to a single-use solution. Accordingly,the capital investment for the user is minimal to convert to the latestin bioreactor technology. In the process, the cleaning associated withprior-art bioreactors, as well as the need for sterilizing thebioreactor, are eliminated.

In addition, since the control system and geometry of the vessel remainthe same as prior to conversion to a single-use solution, the user cancontinue to employ his or her existing protocols and recipes, saving onprocess-development time that would otherwise be required when workingwith a new bioreactor that has a different geometry and differentcontrol parameters.

Headplate 101 allows for many small ports and tubes to be placed in asmall area, allowing this design to be feasibly used for vessel sizesbelow 1 liter. Accordingly, the limitation of conventional stirred-tankbag designs, wherein it is not possible to fit a sufficient number ofports in the bag to create a feasible bioreactor below 50 liters, isovercome by embodiments of the invention.

Embodiments of the invention also address the disposal and storagelimitations that conventional rigid plastic stirred-tank designs pose.Since a large portion of the bioreactor (the vessel liner) is made of aflexible bag-type material, the single-use bioreactor can be compressedto a much smaller volume than its inflated volume, thus saving onstorage space, packaging, and disposal costs.

Finally, this design allows the user to “plug-and-play” the use of asingle-use bioreactor at any time. If the user chooses to revert tousing the original glass bioreactor to compare runs, or simply becausethe user has run out of single-use vessels, the user can easily returnto using his or her original equipment at any time.

Exemplary embodiments have been described wherein particular componentsperform particular functions. However, the particular functions may beperformed by any suitable component and are not restricted to beingperformed by the particular components named in the exemplaryembodiments.

Although the term “vessel liner” is used herein, it is not necessarythat the vessel liner or bag actually be contained within a vessel orother equipment. For example, in one embodiment, bioreactor 100 issuspended from above, without the vessel liner being contained withinany other structure. A vessel liner or bag used with bioreactor 100 cantake many forms and can be flexible, rigid, or semi-rigid.

Reference herein to “one embodiment” or “an embodiment” means that aparticular feature, structure, or characteristic described in connectionwith the embodiment can be included in at least one embodiment of theinvention. The appearances of the phrase “in one embodiment” in variousplaces in the specification are not necessarily all referring to thesame embodiment, nor are separate or alternative embodiments necessarilymutually exclusive of other embodiments. The same applies to the term“implementation.”

Unless explicitly stated otherwise, each numerical value and rangeshould be interpreted as being approximate as if the word “about” or“approximately” preceded the value of the value or range. As used inthis application, unless otherwise explicitly indicated, the term“connected” is intended to cover both direct and indirect connectionsbetween elements.

For purposes of this description, the terms “couple,” “coupling,”“coupled,” “connect,” “connecting,” or “connected” refer to any mannerknown in the art or later developed in which energy is allowed to betransferred between two or more elements, and the interposition of oneor more additional elements is contemplated, although not required. Theterms “directly coupled,” “directly connected,” etc., imply that theconnected elements are either contiguous or connected via a conductorfor the transferred energy.

The embodiments covered by the claims in this application are limited toembodiments that (1) are enabled by this specification and (2)correspond to statutory subject matter. Non-enabled embodiments andembodiments that correspond to non-statutory subject matter areexplicitly disclaimed even if they fall within the scope of the claims.

1. A method for performing bioreactor operations, the method comprising:providing a support structure of an existing bioreactor system; mountinga disposable bioreactor onto the support structure; and performing thebioreactor operations using the disposable bioreactor mounted onto thesupport structure.
 2. The method of claim 1, wherein: the disposablebioreactor defines an interior volume having a circular top surface, acylindrical side wall, and a bottom surface; the disposable bioreactorcomprises: a rigid headplate comprising a circular headplate diskdefining a headplate disk plane and having a headplate disk diameter;and a flexible, cylindrical bag (a) having a circular bag opening and acylindrical side wall having a bag diameter and (b) receiving a culturemedium, wherein: the headplate disk diameter is larger than the bagdiameter; a circular portion of the headplate having a diametersubstantially equal to the bag diameter, forms the circular top surfaceof the bioreactor's interior volume; an extended portion of theheadplate disk extends beyond the top surface of the bioreactor'sinterior volume in the headplate disk plane; and the extended portion ofthe headplate disk enables the bioreactor to be supported by the supportstructure having a diameter larger than the bag diameter, but smallerthan the headplate disk diameter.
 3. The method of claim 2, wherein: theheadplate further comprises a cylindrical headplate collar formed on aninner side of the headplate disk, defining a collar aperture, and havinga cylindrical side wall having a headplate collar diameter smaller thanthe headplate disk diameter, wherein the collar fits within the upperopening of the support structure of the existing bioreactor; the bagdiameter is substantially equal to the outer diameter of the headplatecollar; the side wall of the bag is parallel to the side wall of theheadplate collar; and the inner surface of the headplate collar forms aportion of the interior surface of the cylindrical side wall of thebioreactor's interior volume with the bag forming the remainder of theinterior surface of the cylindrical side wall of the bioreactor'sinterior volume.
 4. The method of claim 3, wherein the bag is sealinglyand permanently coupled to the headplate collar.
 5. The method of claim2, wherein the bag is welded to the headplate to provide a permanentcoupling seal of the bag to the headplate.
 6. The method of claim 2,wherein the bag is heat sealed to the headplate to provide a permanentcoupling seal of the bag to the headplate.
 7. The method of claim 2,wherein the bag is a flexible vessel liner that is fit within a rigidstructure of the existing bioreactor.
 8. The method of claim 7, whereinthe rigid structure is a glass vessel of the existing bioreactor.
 9. Themethod of claim 2, wherein the bioreactor is suspended from abovewithout the bag being contained within any other structure.
 10. Themethod of claim 9, wherein: the bag forms the bottom surface and atleast a portion of the cylindrical side wall of the bioreactor'sinterior volume; and the side wall of the bag is sealingly andpermanently coupled at the bag opening to the headplate such that theside wall of the bag is perpendicular to the headplate disk plane. 11.The method of claim 10, wherein: the rigid headplate has a plurality ofdisk apertures formed therein; and the disposable bioreactor furthercomprises: tubing, for one or more of the disk apertures, extending froman outer side of the headplate disk through the corresponding diskaperture into the bioreactor's interior volume; an impeller shaftextending from the outer side of the headplate disk through acorresponding disk aperture into the bioreactor's interior volume; animpeller connected to an end of the impeller shaft inside thebioreactor's interior volume; and a drive assembly connected to theheadplate disk on the outer side of the headplate disk and rotating theimpeller shaft and the impeller.
 12. The method of claim 11, wherein thetubing comprises at least one inlet tube passing through an inlet portaperture and at least one outlet tube passing through an output portaperture, wherein: the inlet tube provides matter to the culture medium;and the outlet tube extracts matter from the culture medium.
 13. Themethod of claim 11, wherein the drive assembly comprises an extendedportion and a permanent magnet disposed within the extended portion andcoupled to the impeller shaft, wherein, when a motor-driven magnetrotates around the extended portion, the permanent magnet is caused torotate, thereby rotating the impeller shaft.
 14. The method of claim 11,wherein at least one tubing comprises a coiled portion that extends onthe outer side of the headplate disk.
 15. The method of claim 11,wherein: the only access to the bioreactor's interior volume is throughthe disk apertures in the rigid headplate; other than the bag's circularopening which is sealingly and permanently coupled to the headplate, thebag has no apertures that provide access to the bioreactor's interiorvolume; and the cylindrical side wall and the bottom of the bioreactor'sinterior volume have no apertures that provide access to thebioreactor's interior volume.
 16. The method of claim 15, wherein thebioreactor further comprises: a dissolved oxygen sensor coupled to andextending from the headplate, wherein the dissolved oxygen sensordetects dissolved oxygen in the culture medium; a temperature sensorcoupled to and extending from the headplate, wherein the temperaturesensor detects temperature in the culture medium; an exhaust portcoupled to a filter extending from the headplate, wherein the exhaustport permits ventilation through the filter of gas from inside the bag;and a sparger port coupled to a filter extending from the headplate andto a sparger tube, wherein the sparger tube receives a gas through thefilter and injects the gas into the culture medium, wherein: thebioreactor is suspended from above without the bag being containedwithin any other structure; the tubing comprises at least one inlet tubepassing through an inlet port aperture and at least one outlet tubepassing through an output port aperture; the inlet tube provides matterto the culture medium; the outlet tube extracts matter from the culturemedium; the headplate further comprises a cylindrical headplate collarformed on an inner side of the headplate disk, defining a collaraperture, and having a cylindrical side wall having headplate collardiameter smaller than the headplate disk diameter, wherein the collarfits within the upper opening of the support structure of the existingbioreactor; the bag diameter is substantially equal to the outerdiameter of the headplate collar; the side wall of the bag is parallelto the side wall of the headplate collar; the inner surface of theheadplate collar forms a portion of the interior surface of thecylindrical side wall of the bioreactor's interior volume with the bagforming the remainder of the interior surface of the cylindrical sidewall of the bioreactor's interior volume; the impeller shaft and eachtubing extends through the collar aperture on the inner side of theheadplate disk; the bag is sealingly and permanently coupled to theheadplate collar; the drive assembly comprises an extended portion and apermanent magnet disposed within the extended portion and coupled to theimpeller shaft, wherein, when a motor-driven magnet rotates around theextended portion, the permanent magnet is caused to rotate, therebyrotating the impeller shaft; and the bag is welded or heat sealed to theheadplate to provide a permanent coupling seal of the bag to theheadplate.